title: Speckle contrast in near field scattering limited by time coherence.
abstract: The relationship between the speckle contrast of scattered light in near field and longitudinal distance that is perpendicular to scattering surface is investigated. The experiment indicates that when using the laser illumination source with proper time coherence length, the curve of speckle contrast vs. longitudinal distance appears minimum turning point. The position and value of minimum point are decided by the coherence of light and scattering matter. It is easy to obtain the correlation area of scattered light by measuring the minimum point position and the illuminated area. Comparing to traditional scattering technique, this method can simultaneously measure the roughness parameters of surface height variance and surface height correlation area.
authors.affiliation: Key Laboratory of OptoElectronic Science and Technology for Medicine Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
authors.forename: Gaoming
authors.initials: G
authors.lastname: Li
authors.forename: Yishen
authors.initials: Y
authors.lastname: Qiu
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.forename: Shou
authors.initials: S
authors.lastname: Liu
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Huang
mesh_terms: D008027:Light; D012542:Scattering, Radiation; D013499:Surface Properties; D013997:Time Factors